The subject matter disclosed herein relates generally to imaging systems, and more particularly, embodiments relate to methods and systems for reducing noise in images.
Non-invasive imaging broadly encompasses techniques for generating images of the internal structures or regions of a person or object that are otherwise inaccessible for visual inspection. One such imaging technique is known as X-ray computed tomography (CT). CT imaging systems measure the attenuation of X-ray beams that pass through the object from numerous angles (often referred to as projection data). Based upon these measurements, a computer is able to process and reconstruct images of the portions of the object responsible for the radiation attenuation.
During scanning to acquire the projection data, it is desirable to reduce the X-ray dosage received by the subject. One conventional method of reducing the X-ray dosage is reducing the scan time. For example, a length of the scan time may be reduced to minimize the time over which the projections which contribute to the image are acquired. However, reducing the amount of time utilized to acquire the projection data results in fewer projections being acquired and thus fewer measurements contributing to the image reconstruction. Accordingly, information from fewer total measurements is available to reconstruct the final image.
Moreover, reducing the scan time may also result in statistical noise affecting the quality of the projection data. The statistical noise may result in the final image having noise-related imaging artifacts. Conventional imaging systems utilize various techniques to remove the statistical noise and thereby increase the image quality. For example, one conventional de-noising technique utilizes a filter that replaces each pixel by a weighted average of all the pixels in the image. However, the conventional filter requires the computation of the weighting terms for all possible pairs of pixels, making implementation computationally expensive. As a result, a time to generate the final image is increased.